1. Field of the Invention
The present invention relates to a vehicle headlamp system adapted to control the beams emitted from headlamps.
2. Description of the Related Art
Typical conventional vehicle headlamps are incapable of sufficiently irradiating road surfaces ahead of a vehicle when the vehicle is driven on mountain roads, around curves at intersections, and so forth, because the beam emitting directions are fixed.
In this connection, JP-A-8-192674 discloses a vehicle headlamp system designed to improve visibility when a vehicle is running around a curve at an intersection, and the like, by directing beam emission toward a road surface ahead of the vehicle in a curved travel direction when a direction indicator is actuated or when steering is conducted.
In the vehicle headlamp system in the above-described publication, however, unnecessary beam control may be performed because the beam emitting direction is varied with the actuation of the direction indicator, or with steering, even while the vehicle is running in accordance with the road configuration. Further, even when the direction indicator is actuated to change a lane while the vehicle is running on a straight road at a high speed, for example, the beam emitting direction may be varied. In such a case as this, the problem is that the driver may be given a feeling of wrongness.
An object of the present invention, made in view of the foregoing circumstances, is to provide a vehicle headlamp system for allowing a road surface ahead of a vehicle to be sufficiently irradiated without giving a driver a feeling of wrongness.
In order to accomplish the above and other objects, there is selected, in response to the vehicle speed, one of the modes in which beam control is performed in accordance with road configuration ahead of a vehicle, and in accordance with the turning angle of the vehicle.
A vehicle headlamp system according to the invention comprises:
headlamps for forwardly emitting beams from a vehicle;
beam control means for controlling the beams emitted from said headlamps;
road configuration detection means for detecting a road configuration ahead of the vehicle; and
turning-angle detection means for detecting the turning angle of the vehicle,
wherein said beam control means is provided with a road-configuration-corresponding mode in which beam control is performed according to the results detected by said road configuration detection means, and a corresponding-turning-angle mode in which beam control is performed according to the results detected by said turning-angle detection means, and
further wherein one of said road-configuration-corresponding mode and said corresponding-turning-angle mode is selected in response to the vehicle speed.
The contents of the beam controlxe2x80x94performed by the xe2x80x98beam control meansxe2x80x99xe2x80x94are not limited to specific ones, but may include any suitable contents such as: the direction of the beam emitted from each headlamp; the emission range of the beam emitted therefrom; and the emitted quantity of light, or a proper combination of them.
The xe2x80x98road configuration detection meansxe2x80x99 is not limited to specific contents for detection, but may be any suitable means such as a navigation unit and a CCD camera capable of detecting a road configuration ahead of a vehicle.
The xe2x80x98turning-angle detection meansxe2x80x99 is not limited to specific contents, but may be any suitable one such as a steering-angle sensor and a yaw-rate sensor capable of detecting the turning angle of a vehicle.
The contents of the xe2x80x98road-configuration-corresponding modexe2x80x99 and the xe2x80x98turning angle corresponding modexe2x80x99 in which beams are emitted are not limited to specific embodiments described herein.
As shown in the above-described arrangement, the beam control means for controlling the beamsxe2x80x94emitted from the headlamps in the vehicle headlamp system according to the inventionxe2x80x94is provided with the road-configuration-corresponding mode ad the corresponding-turning-angle mode. In the road-configuration-corresponding mode, beam control is performed according to the detected results of the road configuration ahead of the vehicle. In the corresponding-turning-angle mode, beam control is performed according to the detected results of the turning angle of the vehicle, detected by the turning-angle detection means. One of the modes is selected in response to the vehicle speed, whereby the beam emitting direction is prevented from being inadvertently changedxe2x80x94irrespective of the rise and fall of vehicle speedxe2x80x94through the actuation of the direction indicator or the steering operation as before.
Therefore, according to the invention, the vehicle headlamp system so configured as to perform beam control over the headlamps provides the road surface ahead of the vehicle with sufficient irradiation without giving a driver a feeling of wrongness.
The following operation/working effect is achievable. One method of selecting between the aforementioned modes is in response to the vehicle speed. For example, the method may include the steps of performing beam control in the road-configuration-corresponding mode when the vehicle speed is at a predetermined set vehicle speed or higher, and performing beam control in the corresponding-turning-angle mode when the actual vehicle speed is lower than the set vehicle speed.
More specifically, to sufficiently irradiate the road surface ahead of the vehicle, it is basically preferred to perform beam control according to the detected results of the road configuration ahead of the vehicle. However, the lane and course are often changed during traveling at a low vehicle speed in a manner having no connection with the road configuration ahead of the vehicle. Therefore, beam emission in conformity with the actual travel situation of the vehicle can be realized by performing beam control according to the detected results of the turning angle of the vehicle during traveling at a low vehicle speed.
The contents of the xe2x80x98road-configuration-corresponding modexe2x80x99 are not limited to specific described embodiments, as long as beam control is performed according to the detected results of the road configuration ahead of the vehicle. However, if the road-configuration-corresponding mode is constituted of both the road-configuration control mode for carrying out beam emission fit for traveling in accordance with the road configuration, and the intersection-control mode for carrying out beam emission fit for traveling in a curve at an intersection, then smoother beam emission can be carried out and, consequently, the road surface ahead of the vehicle is irradiated still more sufficiently.
When an arriving time or an arriving distance up to the next intersection is of a predetermined value or greater, and when the vehicle speed is a secondary predetermined vehicle speed or higher, it is preferred that beam control is performed in the road-configuration control mode on the assumption that the vehicle will proceed on the traveling road in according with the road configuration for the time being. Thusly, the driver is prevented from being given a feeling of wrongness.
When beam control is performed in the intersection-control mode, if the arriving time to the intersection is less than the predetermined time, and if the direction indicator is in operation, beam emission can be carried out in bilateral turning directions in good time. Consequently, the road surface ahead of the vehicle is irradiated still more sufficiently as compared with a case where beam control is performed in the corresponding-turning-angle mode.
However, when the vehicle speed is not reducible to the marginal turning speed at the next intersection by the time the vehicle 2 reaches that intersection, beam control is preferably performed in the road-configuration control mode, whereby beam control is prevented from being performed in the intersection-control mode, even when the direction indicator is mistakenly actuated or is actuated only to change lanes.
On the other hand, even though the arriving time or the arriving distance to the next intersection is less than the predetermined value, beam control is preferably performed in the road-configuration control mode when the vehicle speed is at the secondary predetermined vehicle speed or higher, and when the direction indicator is unactuated. Thusly, the driver is prevented from being given a feeling of wrongness by uselessly switching the beam control to the intersection-control mode when the vehicle is expected to be running in accordance with the road configuration.
Beam control is preferably performed in the corresponding-turning-angle mode when the steering operation is actually conducted, as when the vehicle travels in a curve at an intersection.